backend/buisnesslogic/src/main/java/com/plannaplan/services/ExchangeService.java

package com.plannaplan.services;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Optional;
import java.util.Set;
import java.util.stream.Collectors;

import com.plannaplan.entities.Assignment;
import com.plannaplan.entities.Commision;
import com.plannaplan.entities.Exchange;
import com.plannaplan.entities.Groups;
import com.plannaplan.entities.User;
import com.plannaplan.models.MatchData;
import com.plannaplan.repositories.ExchangeRepository;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class ExchangeService {

    @Autowired
    private ExchangeRepository repo;

    @Autowired
    private AssignmentService assignmentService;

    @Autowired
    private UserService userService;

    /**
     * @param exchange Instance to save in database
     * @return Exchange Instance contains database id
     */
    public Exchange save(Exchange exchange) {
	return this.repo.save(exchange);
    }

    /**
     * @param id Id of exchange in database
     * @return Optional Exchange if found
     */
    public Optional<Exchange> getById(Long id) {
	return this.repo.findById(id);
    }

    public List<Exchange>  getAllExchanges() {
	return this.repo.findAll();
    }

    /**
     * @param id Id of user
     * @return List of exchanges that belong to user
     */
    public List<Exchange> getByUserId(Long id) {
	return this.repo.getByUserId(id);
    }

    /**
     * @param entity Exchange entity which we would like to delete
     */
    public void deleteExchange(Exchange entity) {
	this.repo.delete(entity);
    }

    /**
     * @param assignment Assignment to trade for
     * @param group      Desired group
     * @return Optional with Exchange if exist
     */
    public Optional<Exchange> checkForExchange(Assignment assignment, Groups group) {
	return this.repo.checkForExchange(assignment, group);
    }

    public void performExchange() {
	final List<MatchData> matchData = this.getMatches();
	final List<Long> performedAssignmentExchanges = new ArrayList<>();
	matchData.forEach( m -> {
		final Assignment assignmentOne = m.getAssignmentOne();
		final Assignment assignmentTwo = m.getAssignmentTwo();

		if (!(performedAssignmentExchanges.contains(assignmentOne.getId()) || performedAssignmentExchanges.contains(assignmentTwo.getId()))){
		    final Commision commisionOne = assignmentOne.getCommision();
		    final User userOne = commisionOne.getCommisionOwner();
		    final Commision commisionTwo = assignmentTwo.getCommision();
		    final User userTwo = commisionTwo.getCommisionOwner();

		    assignmentOne.setCommision(commisionTwo);
		    assignmentTwo.setCommision(commisionOne);

		    userOne.removeGroup(assignmentOne.getGroup().getId());
		    userTwo.removeGroup(assignmentTwo.getGroup().getId());

		    userOne.claimGroup(assignmentTwo.getGroup());
		    userTwo.claimGroup(assignmentOne.getGroup());

		    this.assignmentService.save(assignmentOne);
		    this.assignmentService.save(assignmentTwo);

		    this.userService.save(userOne);
		    this.userService.save(userTwo);

		    performedAssignmentExchanges.add(assignmentOne.getId());
		    performedAssignmentExchanges.add(assignmentTwo.getId());
		}

		this.deleteExchange(m.getExchangeOne());
		this.deleteExchange(m.getExchangeTwo());
	    });
    }

   public List<MatchData> getMatches(){
       final List<MatchData> matches = this.repo.getMatches().stream().map(m -> {
	       final Exchange exchangeOne = (Exchange) m[0];
	       final Exchange exchangeTwo = (Exchange) m[1];
	       return new MatchData(exchangeOne, exchangeTwo);
	   }).collect(Collectors.toList());

       final Set<MatchData> uniqData = new HashSet<>(matches);
       final List<MatchData> matchDataListSorted = uniqData.stream().sorted((m1, m2) -> -1 * m1.compare(m2))
	   .collect(Collectors.toList());

       return matchDataListSorted;
   }
}